Hormonal and nutritional factors which control the biochemistry of fetal lung development and maturation will be studied. Among these factors, prostaglandins and associated prostaglandin compounds, prostacyclin (PG12) and thromboxane A2 (TXA2) will be studied in context with fetal lung maturation as assessed by lecithin production and in context with the pathophysiology of respiratory diseases of the newborn. The role of epidermal growth factor (EGF) in the developing fetal lung will also be evaluated in terms of fetal lung glycogen metabolism and lecithin production as part of the potential hormonal stimuli which promote lung maturation. The effects of and the measurement of EGF will be assessed in the rat throughout the terminal stages of gestation. Human newborn studies will be directed at determining blood and urinary levels of the PG12 metabolite, 6 keto PGF1 varies by radioimmunoassay in infants suffering from respiratory distress in the immediate post partum period. These studies may lend further credence to the involvement of prostaglandins in the pathophysiology of lung disease in the newborn.